Archive for May 26th, 2009

Great, great (loooong) article in PLoS Biology about the vaccine-autism wars, which ironically points to a hidden pitfall in applications of the precautionary principle. I love the science studies (STS) savviness:

[Medical anthropologist Sharon] Kaufman sees the enduring belief in the vaccine–autism theory as an example of what Ludwik Fleck, a clinical microbiologist with a passion for epistemology, called “an event in the history of thought”—a critical step in the way the perception of a scientific fact changes. In the US, that first step came in the form of a simple legislative action that produced new information about what was in vaccines—and quickly fed speculative theories linking them to autism.

In the US, fears centered around the ethylmercury-containing preservative thimerosal after a 1999 government report revealed that three childhood vaccines—diphtheria, tetanus, acellular pertussis (DTaP); Haemophilus influenzae type b (Hib); and hepatitis B—might expose infants to more mercury than anyone had realized.

The ill-fated precaution…:

Given the uncertainty about ethylmercury’s toxicity, Neal Halsey, director of the Institute for Vaccine Safety at Johns Hopkins University, urged vaccine policymakers at the CDC and American Academy of Pediatrics (AAP) to remove thimerosal from vaccines as a precautionary measure and to maintain public confidence in their safety. The agencies agreed, and vaccine manufacturers responded quickly; by March 2001, no children’s vaccines contained thimerosal.

Anticipating the FDA’s release of its findings, the AAP issued a statement explaining its decision as an effort to minimize children’s exposure to mercury, asserting that “current levels of thimerosal will not hurt children, but reducing those levels will make safe vaccines even safer”. Unfortunately, Kaufman says, “rather than reassuring parents, the statement fueled public fears and prompted all sorts of questions.”

… fueled the highly speculative speculation:

Several months later, Medical Hypotheses—an unconventional journal that welcomes “even probably untrue papers”—received and later published a purely speculative article called “Autism: a novel form of mercury poisoning”. Two of the authors, Sallie Bernard, a marketing consultant, and Lyn Redwood, a nurse, had just launched the parents’ advocacy group SafeMinds to promote their thimerosal hypothesis. Although their now debunked theory appeared in a journal that openly eschews peer review and evidence-based observations, several parent advocacy groups still cite it as evidence that mercury in vaccines causes autism.

If you are at all interested in the subject, read the full piece, by writer Liza Gross. Tons of information in there. Like this bit:

Sadly, studies suggest that the burden of lowered immunization rates will likely fall disproportionately on poor people living in crowded conditions, hotbeds of disease transmission, and exacerbate existing health disparities among minority populations—where kids go unvaccinated not by choice but because of limited access to health services.

As long as I’m eating crow, let it be in an area in which I supposedly have some expertise. I finished reading Steven Pinker’s The Blank Slate (The Modern Denial of Human Nature), and I have to say he’s made a pretty convincing argument that a) we often take for granted the idea that a person’s behavioral tendencies are primarily learned, in particular learned from culture, and b) although some of the forms those behaviors take may reflect our cultural context, the tendencies themselves probably do not.

I could quibble with Pinker on some points. He could have strengthened his argument, and expanded the scope of his audience, by acknowledging that culture can and does reinforce the idea that some universal behaviors are more valuable than others. Without that proviso, I think it’s easy for the concept of a “human nature” to end up reinforcing hurtful stereotypes. I also think he glosses over some problems in the field of evolutionary psychology — in particular, an over-reliance on adaptive rationales — for the sake of streamlining his argument for a human nature.

That being said, I disavow my earlier line of argument that Pinker is letting parents off the hook, for reasons I hope to get into soon. And in general, I am starting to agree with his statement in the book’s final chapter:

I suspect that few people really believe, deep down, that boys and girls are interchangeable, that all differences in intelligence come from the environment, that parents can micromanage the personalities of their children, that humans are born free of selfish tendencies, or that appealing stories, melodies, and faces are arbitrary social constructions. … Scholars who publicly deny intelligence is a meaningful concept treat it as anything but meaningless in their professional lives. Those who argue that gender differences are a reversible social construction do not treat them that way in their advice to their daughters, their dealings with the opposite sex, and their unguarded gossip, humor, and reflections on their lives. … The alternative [to acknowledging human nature] is to make intellectual life increasingly irrelevant to human affairs, to turn intellectuals into hypocrites, and to turn everyone else into anti-intellectuals.

Like I mentioned, I hope to find some time in coming weeks to explain how Pinker turned me around.